Engine control device



Sept. '20, 1949. P. SCHNEIDER ENGINE CONTROL DEVICE 3 Sheets-Sheet 1 Filed NOV. 16, 1942 wzw Sept. 20, 1949. 5mm 2,482,559

ENGINE CONTROL DEVI CE Filed Nov 16, 1942 s Sheets-Sheet 2 S p 0, 1949. P; L... SCHNEIDER 2,482,559

ENGINE CONTROL DEVICE Filed Nov. 16, 1943 v 3 Sheets-Sheet 3 a? IEVENTOR Patented Sept. 20, 1949 r r. 2,482,559

UNITED STATES PATENT orslca ENGINE CONTROL DEVICE Paul L. Schneider, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application November 16, 1942, Serial No. 465,671

8 Claims. (01. 170-13514) This invention relates to a control for a superdescription, reference being had to the accomcharged airplane engine whereby a selected manpanying drawings wherein a, preferred embodiifold pressure is automatically obtained and the ment of the present invention is clearly shown. propeller pitch controlling mechanism is auto- In the drawings the four figures of the drawmatically adjusted so as. to coordinate propeller 5 ings are diagrams of the different embodiments or engine speed with the selected pressure. of the present invention.

In the copending application of John Dolza Referring to Fig. 1,a'n engine 20 drives, through and others Serial No. 449,918, filed July 6, 1942, a shaft 2|, a propeller 22 having a propeller pitch there is disclosed a controller unit connected with governing mechanism contained in a unit 23 the engine throttle and manually adjusted so as rotatable with the propellensaid unit having an to obtaina selected manifold pressure which is adjusting lever 24. Fuel mixture for the engine maintained in the desired relation to altitude is supplied by the carburetor 25 connected with variations. This controller provides also for adan induction pipe 26 having a valve 21 and leadjusting the propeller pitch controlling mechaing to a supercharger 28 connected with the ennism incoordinated relation to selected engine gine intake manifold 29. The throttle valve conpressures. For this purpose the controller has troller unit 30 comprises an engine-oil-pressurean operating arm mechanically connected with operated servo-motor which includes a cylinder the propeller pitch controlling mechanism. In 3| and a piston 32 normally maintained at the installations where the propeller and engine are right by a spring 33. Piston 32 is attached to a a short distance apart the mechanical connecrod 34 connected at 35 with a link 36 connected tion between thecontroller of the engine throttle at 31 with a bell crank having arms 38 and 39 valve and the propeller pitch controlling mechaand pivotally supported at 40 on the free end of nism can be easily made. -Where there is relaan arm 4! extending from a shaft 42 to which tively great distance between the propeller and arms 43 and 44 are connected. Arm 39 is conengine, satisfactory mechanical connections benected at 45 with link 46 connected at with tween the controller and the engine, which may arm 48 fixed to a shaft 49 which operates th be behind the pilot, and the propeller pitch v lv 21,

controlling mechanism, which may be near the Lever 44 is manually controlled by the pilot. nose of the airplane, can be made only with great Fig. 1 shows the engine idle position of lever 44. difiiculty. When takingoff, the pilot moves lever 44 counter- '11: i t e for an object of the present inv n clockwise to a predetermined position thereby t10h lie-Provide a un Sep ated o theen i causing pivot 40 to move counterclockwise, since fuel int ke pre su regulating unit, which is the servo piston 32 does not immediately move capable of being mounted adjacent to or toward the left, pivot remains fixed. Therebined with the propeller pitch adjusting mecha- 35 fore the bell crank differential lever arms 38, 39 nism, said unit being under the control of the are caused to rotate clockwise relative to pivot pressure regulating unit and capable of changing 40, thereby causing link 46 to move toward the the Setting of e governed Speed adj m n right, the arm 48 to move clockwise and likewise level of the p opeller pitch ad in mechanism the throttle 21 thereby causing the throttle to be so that the engine speed will be governed in premoved to an open position which is nearly suflidetermined relation to a selected pressure to be ie t for the requirements of take-off. This maintained by the pressure regulating means. movement of arm 44 is accompanied by move- According to the disclosed embodiments of the ment toward the right of a valve 50 which conpresent invention this object is accomplished by trols the passage of engine pressure oil from a providing an electric servo-motor for shifting 40 pipe 4| through a passage 52 to the right side of h po i ion of th v rned speed adjusting lever piston 32. In order to receive this movement, the and a servo-motor controllapparatus u er the valve 50 isrconnected by a rod 53 with a pivot 54 control of the pre ure re ulating means. on the lower end of a lever 55 pivotally supported Further objects and advantages of the present at 56 and having its upper end 51 engaged by invention will be apparent from the following 50 a spring 58 which urges the lever 51 against a 3 cam 50 fastened to a shaft 60 connected by an arm 6| which is connected at 62 with a link 63 connected at 64 with the arm 43. Therefore when the main control lever 44 is moved counterclockwise or toward the right in Fig. l, cam 59 is rotated counterclockwise to permit the spring 58 to move the lever 55 counterclockwise and the valve 50 toward the right to cut off communication between engine oil pressure pipe I and a passage 65 leading to the left end of cylinder 3| and to cause pipe 5I to communicate with passage 52 leading to the right end of cylinder 3|. Then the servo-piston 32 moves toward the left to causefurther opening movement of the throttle 21 to-such extent that a selected engine intake pressure is obtained. In order that this intake pressure will be maintained independentlyof altitude, the movements of the pivotal support 56 of lever 55 are controlled in accordance with engine intake pressure. Pivot'56 is:pr.ovid"- ed by a bridge 10 connectingthe adjacent mov able ends of Sylphons 1| and 12 having fixed ends 13 and 14 respectively. The Sylphon 12- is connected by pipes 15 and 10 with the outlet of supercharger 28. ated so that the bellows system is independent of variations-in pressure of the surrounding atm'osphere. Calibrated springs not shown are 10- catedwithinthe bellows in order that the movements thereof will be properly coordinated with variations in intake manifold pressure. the unit functions to move the valve 21 to obtain aselected intake pressure then further opening-movement. of the valve will be arrested. When the selected pressure is obtained in the bellows- 12, then .thevalve 50 will have been moved into such position as to cover both of the-ports65 andl52-sothat piston 32 will remain in such position as required to maintain the throttle valve 21 in the position-which gives the selected pressure. As the plane increases in altitude-the throttle-21 will be automatically opened wider and wider in order that the selected pressure will be maintained in the desired relation to'altitude. Theishaft I50 of the pressure'selecting; cam 531s mounted eccentrically in a shaft 80, the center of which is indicated by the dot 8-I. Shaft 80 is connected by arm 82 and link 832-with the pivot 35 on rod 34; As rod 34 moves toward. the; left from the position shown, the

shaft 80. moves clockwise thereby causingthe K center of shaft 60 to. move clockwise about the axis 8| of shaft 80. This movement produces a modification of the originally selected position of the cam 59 in such manner that the controller comes intov av state of equilibrium when the intake manifold pressure is slightly less than that actually selected by movement of. the lever 44.. At sea level, this modification is very small, but increases as altitude increases. At critical altitude the modification of the pressure selection is a few percent reduction in the pressure originally selected at sealevel. The advantages of this adjustment are two: namely, (1) account is taken of the fact that. as altitude increases, the exhaust back pressure decreases, therefore it is not necessary to maintain at critical altitude the intake pressure selected for take-01f at sealevel in order that the indicated mean effective pressure of the engine will remain the. same; (2), the controller unit is more stable in operation becausethe movement of the piston 32 toward the left inresponse to the opening of port 52 by valve 50..causes .part of the movement of the valve 50 which closes the port 52. Therefore, a hunting action of the control unit 30 is prevented.

The Sylphon 13 is evacu- When The control unit 30 is described in detail and is claimed in the copending Dolza et al. application which also discloses mechanical means directly controlled by lever 44 for moving an operating arm which is mechanically connected with the propeller pitch governor. In place of a propeller pitch governor controller coordinated mechanically with the unit 30, I provide a separate controller unit I00 comprising an electric servomotor M for shifting the position of the governed speed adjusting lever 24 and motor controlling apparatus under the control of the pressure regulating unit 30 for controlling the servo-motor M to effect a setting of the governedspeed adjusting lever 24 in predetermined relation to a pressure selected to be maintained by the pressure regulating unit. The motor M comprises fields; of opposite polarity IOI and I02 connected through motor brush I03, armature I04, motor brush I05, with battery I06 which is connected with a contact arm I01 driven by shaft 42 of the controller unit 30 through gears I08 and I09 and ashaft'IIil uponwhich the arm I01 is mounted. Arm I01 is engageable with any one of a plurality of stationary contacts III, H2, H3 and H4 connected respectively with wires I2I, I22, and 523 and 1-24 which are connected'with resilient conducting blades 'I3I, I32, I33 and I34, whichare engaged respectivel'yby cams I44, I42, 543 and I44 mounted on a shaft I45 driven by the motor M through speed reducing gears I25, I28, I21 and I28. Shaft I45'drives'speed-reducing gears I35, I33, I3-1-and I38, the latter ofwhich drives an arm I39 connected'by alink I40'with the governed speed adjusting lever 24.

Blade I3I carries contacts 131a; and I3'I'c engageable respectively with contacts I3Ib and I3Id. Blade I32 carries contacts [32a and I320 respectively engageable with contact I321) and I32d. Blade I33 carries contacts I33a, and I330 respectively engageable. with contacts I331) and I33d; Blade I34 carries a contact I340 normally engaging contact I34c and a contact I34a for making, engagement, with a contact I341). The upper side contacts I3I1), I321), I331) and I341) are connected by wire I5! with the field winding IDI and the lower side contacts I3Id,. I32d, I33diand 534d are connected by wire I52 with motor field winding I02. Contact arm. I01 has four positions corresponding .to four control positions of lever 44, namely: idle, minimum, cruise, take-off and emergency. These four positions effect the selection of different fuelintake pressures to be maintained. Coordinated with these four intake pressures are four governedspeeds to be maintained, namely, those corresponding to=four positions 241, 2.42, 243 and 244 of the governed speed adjusting lever 24. When lever 44 is at idle'positionas shown, contact arm I01 is on contact I I I and lever 24 is at 241. Movement of lever 44 counterclockwise to minimum cruise position moves arm I01 to contact II2 which so affects the motor control system that the motor M will move the lever 24 from 241 to 242. Movement of lever 44 from minimum cruise position to takeoff positionmoves arm I01 to contact II3 which so affects the motor control system that motor M will move lever 24 from 242 to 243. Movement of lever 44 from minimum cruise position to emergency position moves arm. I01 to contact 4 which -so affects the motor control system that motor M will move lever 24from. 24; to244. Movement of lever 44 clockwise with its various positions causes corresponding, clockwise movementsof arm 24 totake place.

In order that the motor control system will be affected in the manner described, the cams I4I, I42, I43 and I44 are shaped, as shown'in Fig. 1 to produce the results given in the following I 34 other combinations between positions of lever 44 and positions of lever 24 can be eifected.

In the form of the invention shown in Fig.2, the servo-motor M has its field winding 2! and schedule: I opposite polarity connected respectively with Motor has stoppedwith arm 107 at with arm 107 at with arm 107 at with arm 107 at contact 111 contact 112 contact 113 contact 114 Cam 141 upper and lower conupper contacts closei. upper contacts closed upper contacts closed.

tacts open. Cam 142 lower contacts closed" upper and low r 0011- .do Dc.

tacts open. Cam 143 lower contacts closed. upper and lower 0011- Do.

tacts open. lower contacts closed. lower contacts open. at 242 at 24c. Lever 44 ta e-0 f emergency.

When lever 44 is at idle, arm I0! is on contact III, and the motor M is at rest since contacts I3Ia and I3Ib are separated. If pressure selecting lever 44 is moved right to minimum cruise position arm I01 is caused to engage contact H2 and motor M is energized through the circuit including contacts I320 and I32d. Motor M rotates the gears and cams in the direction of the arrows until cam I42 has engaged blade I32 and caused contact I320 to be separated from contact I32d. When lever 44 moves to take-oil position and arm III! has been moved into engagement with contact II3, motor M will operate until cam I43 has engaged blade I33 and has caused separation of contacts I330 and I33d. When lever 44 moves to emergency position and arm I01 engages the stationary contact II 4, motor M will operate until the cam I44 elevates to blade I44 to separate contact I34c from contact I34d.

In order that the lever 24 may be rotated clockwise from position 244, it is necessary that the cams I4I, I42 and I43 be so constructed that by the time that cam I 44 has lifted contact I340 away from contact I34d the other cams will have lifted the various blades I3I, I32 and I33 to such extent that the upper side contacts will be electrically connected with the blades. Therefore, when movable contact I0! is moved away from contact II4 into engagement with Contact II3, a circuit will be established which includes motor field winding I0 I. Therefore, motor M will rotate the cams and gears in directions opposite to that indicated by the arrows in order to move the lever 24 from position 244 in position 243 at which position contact I 33a would be separated from contact I33b. Likewise when movable contact I01 is moved away from contact I I3 into engagement with contact H2 a circuit would be established by contacts I3'2a and I32b with motor field winding I M Therefore, motor M would rotate the cams and gears in directions opposite to that indicated by the arrows in order to move lever 24 from position 243 to position 242 at which position contact I32a would be separated from contact I32b. Likewise when movable contact I0! is moved away from contact I I 2 into engagement with contact I II a circuit would then be established by contact I3Ia and I3Ib with motor field winding IOI thereby causing motor M to rotate the cams and gears in directions opposite to that indicated by the arrows, thereby causing lever 24 to move from the position 24 to position 241 in which position of the lever 24, the contact I 3I a would be separated from contact I3 lb.

By changing the connections between contacts III, H2, H3 and H4 and levers I3I, I32, I33 and 20 contacts 203 and 204 of relays 2I I and H2 adapted to be engaged by contacts 25and 206, respectively, carried by flexible blade armatures 201 and 208 respectively, connected by wire 209 to positive terminal 2I0 of battery B. The magnet coils 2 I 3 and 2 I 4 of said relays are connected with wire 209 and the contacts 2 I5 and 2I6 of a galvanometer operated switch 220. Contacts 2I5 and 2 I 6 are engaged respectively by contacts 2| 7 and 2I8 carried by arm 2I9 of the switch 220. Arm 2I9 is rotated in one direction or the other depending upon the direction of current flow through galvanometer coil 22I Contacts 2I1 and 2I8 are connected with wire 222 connected with wire 223 connecting motor M with regulator terminal 224 of battery B.

A bare wire potentiometer coil 225 is connected with the battery terminals 2H! and 224. Coil 225 is engaged by a metal wiper blade 226 pivoted at 221 and carrying a roller 228 urged by a spring 229 against a cam 230 carried by a shift 23! driven by motor M through speed-reducing gears 232. A bare wire potentiometer coil 235 is connected with the battery terminal 2!!! and 224. Coil 235 is engaged by a metal Wiper blade 236 pivoted at 23! and carrying a roller 238 urged by a spring 239 against a cam 240 carried by a shaft 24I driven by shaft 42 of pressure regulator unit 42 through gears 242, 243 and 244. Galvanometer coil 22I is connected with wiper blades 226 and 236. Shaft 23I drives an arm 250 connected by link 25I with the governed speed adjusting lever 24.

The operation of the form shown in Fig. 2 is as follows: When lever 44 is moved to effect a selection of pressure to be maintained by unit 30, wiper blade 236 is moved into a predetermined position with respect to coil 235. That position depends upon what pressure has been selected by movement of lever 44. If the relation of the wiper blade 226 to the coil 225 is not then the same as the predetermined relation between blade 236 and coil 235, current will flow through the galvanometer coil 22I in one direction or the other depending upon the sense in which these relationships difier. If blade 226 is too far down, arm 2I9 will turn clockwise to close contacts 2I6, 2I8 thereby energizing coil 244 of relay 2I'2 to cause contacts 204, 206 to close to cause motor M to operate with field coil 202 energized. Motor M will rotate cam 230 clockwise to allow spring 229 to force blade 226 upwardly to bring the potentiometer coils 225 and 235 into balance. When this occurs, no current flows through galvanometer coil 2'2I and the arm 2I9 returns to mid position and motor M stops after having moved the governed speed 'ad- 7.- justing lever 24 clockwise into a predetermined relationto-the pressureselecting lever 44. This predetermined relationcan be established if arm 24 hasbeen moved too far to the right of its correct position. In that case the wiper blade 226 would have been too far up at the time blade 236 had been placed in this predetermined re1ation to arm 34 when latter had been moved to a certain pressure selecting position. When wiper arm 226 is too far up, galvanometer arm 219 moves counterclockwise to engage contacts 215, 211 thereby energizing relay magnet coil 213 thereby closing contacts 203, 2115 and causing motor M to rotate in the opposite direction with its field coil 231 excited. As cam 230 is moving counterclockwise to establish the same relation between wiper 223 and coil 225 as exists between wiper 236 and coil 235, lever 24 is moving counterclockwise. When the'relation between wiper 226 and coil 225 becomes the same as exists between wiper 236 and coil 235, no current flows through galvanometer coil 221; and arm 219 returns to mid-position and the motor M stops, leaving arm 24 in the correct predetermined relationto arm 44. Therefore arm 24is caused to follow arm 42 according to whatever rule is in order for a particular engine. This rule determines the contour of the two cams 233and 242 whichare the same in contour. The illustrated cams 232 and 24D provide for such controlof motor M that lever 24 moves counterclockwise from a low governed speed positionto a highgoverned speed position when lever 44 moves counterclockwise from a lower pressure selection to a higher pressure selection. If, for an intermediate pressure selec- A tion, the engine requires an adjustment of governed speed to a value which is lower the speeds desirable for engine idling pressure and engine maximum pressure, the cams 23D and 243 would be shaped so as to meet this requirement.

In the form shown in Fig. 3, the servo-motor M is under the direct control of fuel intake pressure communicating through pipes 16 and 323 with bellows 32'! connected by bridge 325 with aneroid 323 in order that the control will not be affected by changes in atmospheric pressure. Bridge 325 carries a pivot 324 for a lever 322 having a fixed pivot 323 and having a fork 321 engage the free end of a lever 319 of a pressure controlled switch unit 320. The switch unit 323 includes contacts 31? and 31.8 carried by lever 31% and engageable respectively with contacts 315 and 3&5 mounted respectively on arms 315a and 313a and urged respectively toward stops 3150 and tits, by springs sitb and 3l5brespectively. Wire 3592;) connects lever 3 I 3 with battery terminal 224. Contacts 315, 311 control relay magnet coil H3; and contacts 313, 318 control relay magnetco-il 2M. Pins 313e, 3160 are mounted ona disc 33B driven by a shaft 331 drivenby motor M through speed reduction gearing 332. Shaft 33! drives gear 333 which drives gear 334 which drives gear 3.3.5 which drives gear 336 which drives arm 359 connected by a link 351 with governor speed adjusting lever 24.

Normally the contacts 311, 318 tog-ether stand midway between side contacts 315, 318 held away from contacts 311, 318 by pins 315a and 3160 respectively. When intake pressure increases, pin 324 moves right and arm moves counterclockwise. Contact 318 engages contact 316 and motor M operates with field 232 excited to cause disc 330 and gear 333 to rotate counterclockwise, hence arm 350 and lever 25 to rotate counterclockwise. This rotation continues until pin .3160 has moved sufficiently to separate contact 316 fron pontact 318. The extent of movement of lever 24;is. d etermined by the extentof movement ofpins 316;: before contacts 313,313 separate. Theexten-t of this movement is determined by the amount of increase in pressure. Likewise, when the intake pressure decreases, lever 322 and contact 3" move left to engage contact 315 and motor M will operate with field coil 231 excited to cause clockwise rotation of disc 331i and gear 333, and hence clockwise rotation of arm 35i] and governed speed adjusting lever 25. Motor M will stop when pin, 3150 has moved left sufficiently to separate contacts 325 31?. The extent of clockwise movement of disc 33!), arm 3% and lever 24 is deter.- mined by extent of movement of pivot pin 324 to. the left as bellows 321 contracts due to decrease in intake pressure. When constructed according to Fig. 3, the device provides for increasing governed engine speed as the value of the selected intake pressure increases.

If it is required that governed speed and selected pressure be coordinated according to some other rule, Fig. 3 is modified as shownby Fig. 4. Gear 333 drives a cam plate 362 having a slot 361 receiving a roller carried by a bellcrank lever arm pivoted at 36- 3 and operating anarm 335 connected by link with arm 24. The cam slot 365 is designed to follow the rule of coordination of the movements of levers 44 and 24.

Vthile the embodiments of the present. inventicn as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. Apparatus for coordinating changes in the governed speed of an aircraft engine with changes in the regulated fuel intake pressure comprising the combination with an engine hav-- ing a throttle valve and a variable pitch propeller driven by the engine and having a governed speed adjusting lever, of an electric servo-motor for shifting the position of the lever, pressure regue lating means for shifting the position of the throttle va1ve for maintainin a selected pressure in the engine intake and including manually con.- trolled means for varying the selection of the pressure tobe maintained, and means under the control of the pressure regulating means for con.- trolling the servomotor to effect a setting of the governed speed adjusting lever in predetermined relation to the selected pressure.

2. Apparatus for coordinating changes inthe governed speed of an aircraft engine with changes in the regulated fuel intake pressure comprising the combination with an engine having a throttle valve and a, variable pitch propeller driven by the engine and having a governed speed adjust.- ing lever, of an electric servo-motor for shifting the position of the lever, pressure regulating means for shifting the position of the throttle valve for maintaining a selected pressure in the engine intake and including manually controlled means for varying the selection of the pressure to be maintained, a current source, circuits including limit switches respectively for determining the extent of movement of the governed speed adjusting lever by the electric motor, cams operated by the motor and cooperating respectively with the limit switches, said cams being shaped respectively to cause the functioning of the limit switches to stop the motor after varying amounts of movement of the motor have taken place, and means controlled by the manually operated pressure selecting means of the pressure regulator for Selectively connecting the-limit switches in circuit with the motor-and current source, whereby the servo-motor operates to efiecta setting of the governed speed adjusting lever in predetermined relation to selected pressure;-

3. Apparatus for coordinating'changes in the governed speed of an aircraft engine with changes in the regulated fuel intake pressure comprising the combination with an engine having a throttle valve and a variable pitch propeller driven by the engine and having a governed'speed adjusting lever, of an electric servo-motorfor shifting the position of the lever, pressure regulating means for shifting the position of the'throttle valve for maintaining a selected pressure in the engine intake and including manually controlled means for varying the selection of the pressure to be maintained, said electric motor having two fields reversely wound to obtain rotation of the motor in either direction, a current source having one terminal connected withrthelmotor, a plurality of limit switches each having side contactsland a movable member capable of making electrical connection with either of the side contacts, a circuit connecting one of the motor fields withone side contact of each-limit switch, a circuit connecting the other motor field with the other side contact of each limit switch, cams operated by the motor and operated respectively to move the movable members of the limit switches, said cams being shaped respectively-to-cause the functioning of the limit switches to stop the motor after varying amounts of movement of the motorhave taken place, and means controlled by the manually operated pressureselectin means of the pressure regulator for selectively connecting the movable members of the limit switches in circuit with the motor and current source, whereby the servo-motor operates to efiect a setting of the governed speed adjusting lever in predetermined relation to selected pressure.

4. Apparatus for coordinating changes in the governed speed of an aircraft engine with changes in the regulated fuel intake pressure comprising the combination with an engine having a throttle valve and a variable pitch propeller driven by the engine and having a governed speed adjusting lever, of an electric servo-motor for shifting the position of the lever, pressure regulating means for shifting the position of the throttle valve for maintaining a selected pressure in the engine intake and including manually controlled means for varying the selection of the pressure to be maintained, a, current source, motor control circuits respectively for connecting the electric motor with the source for operation of the motor in opposite directions, a galvanometer having a movable member and an operating coil, switching means under the control of the galvanometer member for selectively completin said motor control circuits depending on the direction of movement of the galvanometer member from neutral position, similar potentiometer resistances connected in parallel with the current source, movable resistance contactors connected with the galvanometer operating coil, means operated by the manually operated pressure selecting means of the pressure regulator for moving one of the resistance contactors in order to upset the balance of the potentiometers and to obtain a movement of the galvanometer member to efiect an operation of the electric motor, and means operated by the electric motor for moving the other resistance contactor in order to reestablish the balance of the potentiometers and the cessa--- tion of movement of the electric motor whereby the electric motor operates toefiectasetting of the governed speed adjusting lever-in predetermined relation to selected pressure.

5. Apparatus for. coordinating changes in the governed speed of anaircraft engine withchanges in the regulated fuel intake pressure comprising the combination with anengine having althrottle' opposite directions, switching, means responsive to engine intake pressure under the'controlof. the-pressure regulator for selectively completing said motor control circuits for causing the, motor to move the governed speed adjusting lever,;and

means operated by the electric motor for disconnecting the selected. motor control circuit when themotor has operated sufiiciently to move the overned speed adjusting lever into a position having a predetermined relation to the pressure to be maintained by the pressure regulator.

6. Apparatus for coordinating changes in the governed speed of an aircraft engine with changes in the pressure maintained in the engine intake comprislngthe combination with an engine having a variable pitch propellerdriven thereby and provided with a governed speed adjusting lever for controlling the propeller pitch and having an adjustable throttle valve for controlling the intake pressure, pressure regulating means for variably positioning the throttle valve to maintain some selected pressure in the engine intake, a manually operable member movable to different positions to select different pressures to be maintained, a current source, an electric servo motor in circuit with said current source and operable to move the speed adjusting lever to change the propeller pitch, a series of switches between the current source and the one motor for variably controlling the operation of said motor and effective to stop the motor when opened, a plurality of members operable by the motor to open said switches after'dii'ferent degrees of operation of said motor, and means operable by the selector member for connecting the difierent switches of said series with the current source as the selector member is moved to different positions to select different pressures to be maintained in the engine intake whereby the propeller pitch adjusting lever is moved to different positions.

7. Apparatus for coordinating changes in the governed speed of an aircraft engine with changes in the pressure maintained in the engine intake comprising the combination with an engine having a variable pitch propeller driven thereby and provided with a governed speed adjusting lever for controlling the propeller pitch and having an adjustable throttle valve for controlling the intake pressure, pressure regulating means for variably positioning the throttle valve to maintain some selected pressure in the engine intake, a manually operable member movable to difi'erent positions to select different pressures to be maintained, a current source, an electric servo motor in circuit with said current source and operable to move the 111 speed adjusting clever LntO change the propeller pitch a series of switches between the current sourcerand the onetmotor ior'variably controlling theoperation ofsaidmotor. and efiective to stop the motor when opened; lazplura'lity :of members operable by the motor to open said switches after 'idifierent degreesflof operation of said motor, a secondser-ies of switches each of which is in Cir?- lcuitrwith one. of thesfirst series of switches and each of which when closed connects one of: said first series oi s-witches with the current source, andzmeans operable by: the selector member for closing "one or theother of said second series of switches as the selector member is moved to different positions, whereby. the propeller pitch ad- Justing :lever is moved to :difi'erent positions as saidselector memberis moved to select different pressures to be maintained in the engine intake.

'8. Apparatus forcooriiinating changes in the governed speed of an aircraft engine with changes in-the pressure maintained in the engine intake comprising the combination-with an engine havingta variable'pitch propeller driven thereby. and provided with a governed :speed adjusting lever for controlling the propeller pitch and havingan adjustable. throttle valve for controlling the intake pressure, pressure regulating means for variably'positioning the throttle valve to maintain somesele'cted pressure in the engine intake, a manually operable member movable to difierent positions to select different pressures to be maintained, a current source-van electric servo motor in circuit with-said current source and operable to :move thespeed adjusting lever to change the propellerpitch, .a. series of switches between the current source and the one motor for variably 12 controlhnetheoperation of. saidmotor andzefiective to stopithe motor whenppened, a. series of -.difler.entia1;cams eachzof whichisassociated with one of Seidwswitehes sandzoperableby the motor to 'effectnopening of said switches waiter different degrees of rotation of said motoiya second series "of switches each tofwhichis 'incircuit with one 10f thelfirst series ,ofswitches and each err-which whenzclesed com ectssone oi saidfirst series of sw tches with the curren source, and means operable by theeselector meinber- {or closing one or th other of said second series of switchesas the selector n'ember iswinoved. todifierent positions, he e y-theprope i r pit h ad ust ng l ver is moved to difieren po iti nses said selector membe mov d o fierentpressures to maintained :i h eng e intake.-

-UL 'L. SCHNEIDER.

I REFERENCES CITED "The following references'are of record in the filetntthis: patent:

' ST ES PATENTS 

